Ionic Modulation of Ferromagnetic and Proximity‐Induced Magnetization in Co/Pd Heterostructures

Abstract

AbstractDespite the rampant discovery of tunable magnetic properties using magneto‐ionic gating, e.g., magnetic anisotropy, exchange bias, and exchange interactions, there are few studies that give a quantitative understanding of the reversible and irreversible effects of ionic infiltration. In this study, in situ vibrating sample magnetometry, superconducting quantum interference device magnetometry, and X‐ray magnetic circular dichroism (XMCD) reveal the reversible and irreversible control of magnetization, anisotropy, proximity‐effects, spin, and orbital angular momenta. Pd/Co/Pd trilayers, loaded using solid‐state hydrogen‐ion gating, show a decrease in the saturation magnetization of Co, and an increase in the proximity‐induced moment of Pd. This results in little to no change in the net effective magnetization, yet, allows for the effective anisotropy to be reversibly controlled by 270 kJ m−3. The reversible control of the effective anisotropy is dominated by a reversible change in surface anisotropy, however, under repeated cycling, irreversible evolution occurs in the heterostructure. XMCD measurements indicate this is partly due to hydrogen‐induced modification of the spin and orbital angular momenta. Together, these measurements indicate that the origin of the reversible and irreversible effects of magneto‐ionic gating is interfacial and provides crucial insight to scale and optimize thin film heterostructures for enhanced longevity and faster response time.